Disability rates are extremely high in older coronary patients. Determinants of disability were studied in a total of 40 patients (31 men, 9 women), age 65-88 years (mean 72 + 6 years) with chronic coronary artery disease (CAD). All patients were community dwelling and at least 6 months since a diagnosis of acute myocardial infarction (N=15), coronary artery bypass surgery (N=13) or had chronic stable angina pectoris (N=12). Disability was measured using the physical function scale of the Medical Outcomes Study questionnaire (MOS SF3) scaled 0-100, applied to the home setting. Data collection included clinical questionnaires, exercise stress testing with echocardiography and measurement of peak aerobic capacity, body composition analysis by dual x-ray absorptiometry, handgrip and leg-extensor strength, a depression score, a nutrition questionnaire and the SF36 quality of life questionnaire. The best predictors of physcial function score are peak aerobic capacity and the depression score. Handgrip and leg extensor strength were also significant univariate predictors as was percent fat mass. Measures of left ventricular systolic and diastolic function at rest and exercise and body composition measures did not predict physical function score. In contrast, the best predictors of peak aerobic capacity (Peak VO2) were exercise cardiac output, exercise ejection fraction and lean body mass. Physical function scores are lower in older women than in older men. These data suggest that interventions aimed at increasing aerobic capacity and strength, and at decreasing mental depression would improve physical functioning in older CAD patients.